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European hake - Western Ionian Sea
Fact Sheet Title  Fact Sheet
Stock status report 2021
European hake - Western Ionian Sea
Fact Sheet Citation  
Merluccius merluccius - Western Ionian Sea (GSA 19)
Owned byGeneral Fisheries Commission for the Mediterranean (GFCM) – ownership
Monitoring Range Min2014.
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Species List:
Species Ref: en - European hake, fr - Merlu européen, es - Merluza europea, ru - Мерлуза восточноатлантическая
ident Block European hake - Western Ionian Sea
Aq Res
Biological Stock: No         Value: Sub-Regional
Management unit: Yes        Reference year: 2019
 
 
Aq Res State Trend
Aq Res State Trend
Aq Res State Trend Aq Res State Trend
Aq Res State TrendIn overexploitation (F/Ftarget = 2.32)Not applicable
Aq Res State TrendRelative high biomassNot applicable
Aq Res State Trend
Aq Res State TrendNot applicable

In overexploitation, with relatively high biomass.
[The GFCM methodology to provide stock status and management advice is described in the Appendix F of the Sixteenth Session of the Scientific Advisory Committee Report. See the Bibliography section.]
Habitat Bio
Climatic Zone: Temperate.   Bottom Type: Soft bottom; Hard bottom.   Depth Zone: Shelf (50 m - 200 m); Slope (200 m - 1000 m).   Horizontal Dist: Neritic.   Vertical Dist: Demersal/Benthic.  

Water Area Overview
Spatial Scale: Sub-Regional

Water Area Overview
Aq Res Struct
Biological Stock: No


Stock assessment in the GFCM area of application is often conducted by management units, based on GSAs. This method does not ensure that the whole stock is assessed, since stocks may cover several different management units. In some cases, when there is scientific evidence of a stock spreading through different GSAs, as well as information on species from different GSAs, existing information is combined across GSAs. This is then defined as a “joint stock assessment of a shared stock”. The GFCM recommends that when scientific evidence of shared stocks exists, joint stock assessments should be attempted. A number of activities aimed at achieving a better definition of stock boundaries are currently being conducted at the GFCM level. [The State of Mediterranean and Black Sea Fisheries, 2016]
Exploit
 

Following the twenty-first SAC meeting (Egypt, June 2019), the benchmark stock assessment of European hake was carried out assuming the stock in the boundaries of the western Ionian Sea (GSA 19). European hake represents one of the most important demersal species in terms of landing and income in GSA 19, especially for longlines (20 percent of the European hake landing), gillnets and trammel nets (20 percent of the European hake landing), but also for trawlers (60 percent).
Bio Assess
 
Data

Official landings are from DCF (2002-2019) and MEDITS survey indices (available from 1994, used from 2002 to 2019). The discard data are present from 2006 to 2019 with a gap in 2007 and 2008 (not mandatory). In the years 2004, 2005, 2007 and 2008 discard (weight and LFDs) was estimated according to the average discard ratio of the years 2006 and 2009. Biological information on von Bertalanffy growth parameters, maturity at length and length-weight relationship were derived within DCF (2002-2019). The natural mortality vector was estimated as an average of different methods (Gislason, Prodbiom revised version with unique solution, Chen and Watanabe, Brodziak (2011 and 2012), Lorenz and Gulland), consistently with the approach used in the benchmark assessment of European hake in the Adriatic Sea in 2019. Deterministic age slicing using DCF growth parameters was used to produce catch-at-age input for assessment.
Assess Models
Type:  Age-structured
a4a

SCAA a4a (FLR, http://flr project.org/FLa4a) was performed at the European hake benchmark meeting (GFCM, 2020). The original survey catchability submodel used for the benchmark assessment resulted in high instability of the present assessment, in particular the original qmodel <- list(~factor(age), gcv = 0.5). It was replaced by a model assigning equal catchability at ages > 2, that was also considered at the benchmark (GFCM, 2020), having the similar goodness of fit diagnostics (gcv = 0.5) as the model accepted at the benchmark (qmodel <- list(~factor(age)). Fishing mortality and stock recruit submodels remain the same as used for the benchmark assessment.
Results

The results showed a decreasing pattern for fishing mortality that in 2018 was still well above the proxy of F0.1 (0.14), with a ratio of 2.32. The SSB shows some increase in the recent years, while the recruitment is stable.
Sci Advice

Reduce fishing mortality. STF available.
Management
Management unit: Yes
Sources
 
FAO. 2021. General Fisheries Commission for the Mediterranean. Report of the twenty-second session of the Scientific Advisory Committee on Fisheries, online, 22–25 June 2021. FAO Fisheries and Aquaculture Report No. 1347. Rome.  Click to openhttps://www.fao.org/3/cb7622en/cb7622en.pdf
Report of the Working Group on Stock Assessment of Demersal Species (WGSAD). Online, 18–23 January 2021.  Click to openhttps://www.fao.org/gfcm/technical-meetings/detail/en/c/1412431/
Stock assessment form for European hake in GSA 19 (reporting year: 2020).  Click to openhttps://gfcmsitestorage.blob.core.windows.net/documents/SAC/SAFs/DemersalSpecies/2019/HKE_GSA_19_2019_ITA.pdf
Bibliography
 
FAO. 2020. The State of Mediterranean and Black Sea Fisheries 2020. General Fisheries Commission for the Mediterranean. Rome.  Click to openhttps://www.fao.org/3/cb2427en/cb2427en.pdf
FAO. 2016. The State of Mediterranean and Black Sea Fisheries. General Fisheries Commission for the Mediterranean. Rome, Italy.  Click to openhttps://www.fao.org/3/i5496e/i5496e.pdf
FAO General Fisheries Commission for the Mediterranean/Commission générale des pêches pour la Méditerranée. Report of the sixteenth session of the Scientific Advisory Committee. St. Julian’s, Malta, 17–20 March 2014/Rapport de la seizième session du Comité scientifique consultatif. Saint Julien, Malte, Malte, 17-20 mars 2014. FAO Fisheries and Aquaculture Report/FAO Rapport sur les pêches et l’aquaculture. No. R1102. Rome. 2015. 250 pp.  Click to openhttps://www.fao.org/3/i4381b/i4381b.pdf
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